![]() ![]() Due to their high economic and ecological value, oysters have been the subject of major restoration efforts nationwide. This loss is especially problematic because vast oyster reefs once provided a variety of ecosystem services, including the production of a commercially valuable product (oysters), the stabilization of sediments and the physical buffering of exposed shorelines, the creation of shelter for fishes and invertebrates, and the top-down control of now pervasive phytoplankton blooms (Coen et al., 2007). The reef-building eastern oyster Crassostrea virginica has seen dramatic declines along the US Atlantic and Gulf of Mexico coastlines as a result of overharvesting and disease, among other factors (Kirby, 2004, MacKenzie, 2007). These results suggest both a strong predator control in this system and that adding chemical cues are not likely to be an effective restoration strategy. However, recruitment was significantly higher on blocks shielded from predation. Again, we found no enhancement of recruitment to blocks with live oysters or with cue added. We repeated the experiment with the addition of anti-predation cage treatments (with partial cage controls). In our preliminary experiment (Experiment 1), recruitment of oysters was lower to blocks with live oyster or GGR, counter to our expectation. Recruitment was therefore monitored on substrata with settlement cues (live oyster or shell with GGR) and no settlement cues (dead shell only). In the first experiment, half of the blocks received discs that diffused the tri-peptide Glycyl-Glycyl-Arginine (GGR), a potent analog for natural settlement inducers, and only blocks with dead shell received GGR in the second experiment. For both experiments, either dead shell or live oysters were cemented to patio blocks. This study highlights the advantages of augmenting habitat in a manner that provides vertical relief from sedimentation.We conducted two field experiments to test the hypothesis that recruitment of the eastern oyster, Crassostrea virginica, could be enhanced through the selective deployment of artificial settlement cues. Collectively, the data suggest that building thicker shell beds might increase the longevity of a constructed shell bed, and therefore, this approach is recommended for future restoration activities in southern California. lurida oyster density compared with unmanipulated plots and increased oyster density relative to the average density of oysters measured elsewhere in Newport Bay. Overall, augmenting mudflat habitat with oyster shell significantly increased adult O. There was no significant effect of shell deployment method on shell cover, recruitment, or adult density however, spatfallwas greater on loose shell beds comparedwith bagged shell beds in the final year of the study. Shell cover, oyster spatfall (settlement), oyster recruitment, and adult oyster densities were analyzed over 2 y 12-cm-thick oyster beds maintained higher shell cover, experienced less sedimentation, and received greater numbers of oyster recruits than 4-cm-thick beds. Replicate ( n = 5) 2×2 m shell beds were constructed of two initial shell planting thicknesses (bed thicknesses of 4 versus 12 cm) and two methods of deployment (bagged versus loose shell). Several commonly used oyster restoration techniques were examined to determine which would be the most successful for restoring the Olympia oyster Ostrea lurida in Newport Bay, CA. Worldwide oyster population declines have been dramatic and efforts to restore declining populations and the services they provide are ongoing. Oysters provide habitat, sediment stabilization, and improved water quality, and are important foundation species in many estuarine ecosystems. ![]()
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